This invention relates generally to plows and more particularly to an improvement in snowplows and similar devices for cleaning snow and other debris from roadways and similar surfaces.
The invention is particularly applicable to a snowplow apparatus and construction, whereby an improved plow is provided and will be described with particular reference thereto. However, the invention may have broader applications and could be used for other applications such as agricultural purposes and the like.
Assignee""s U.S. Pat. No. 4,845,866 issued Jul. 11, 1989 and U.S. Pat. No. 5,088,215 issued Feb. 18, 1992 are incorporated by reference herein and made a part hereof. The patents are incorporated by reference herein so that details of plow construction known in the art need not be restated herein. The patents incorporated by reference herein are background patents and do not form part of the present invention.
A plow of the type used to remove snow from a roadway includes a blade which rolls the snow upwardly and then moves it transversely across the face of the blade. To accomplish this, the plow includes a moldboard having a curvilinear configuration which terminates in a lower plowing edge or a scraper blade. The scraper blade usually extends in a forward direction and, in effect, digs into the snow and forces the snow onto the curvilinear moldboard. The contour of the moldboard imports a rolling action to the upwardly moving snow and forces the snow transversely across the face of the moldboard and to the side of the plow.
Over the years, many different moldboard configurations of various curvilinear shapes have been experimented with to arrive at a shape which would insure smooth rolling and transverse movement of wet and powdery snow across the moldboard face. A curvilinear configuration, essentially arcuate in shape and extending in only one planar direction has proven an acceptable, widely used geometrical configuration for the moldboard.
A typical snowplow construction is to roll a mild steel carbon plate, typically of about xe2x85x9xe2x80x3, into an arcuate shape to form the moldboard. The framework, typically constructed from structural angle members, is then welded to the rear side of the moldboard to support and prevent the moldboard from fracturing when being hit by rock and other debris from the roadway while also providing a structure for the attachments necessary to operate the plow. Typical examples of such construction may be found by reference to U.S. Pat. Nos. 3,432,947 to Peitl and 3,465,456 to Meyer assigned to the current assignee.
From a consideration of plow weight, a steel moldboard is undesirable. It obviously places greater force requirements on the vehicle to which it is attached, and perhaps more importantly requires heavier plow attachments and larger lifting systems than what otherwise may be possible.
From an efficiency consideration, a number of attempts have been made to improve the efficiency of the steel moldboard in plows of the aforesaid type so as to better enhance the rolling motion and transverse movement of the snow across the face of the moldboard. Many of the approaches fundamentally involve a lowering of the coefficient of friction at the surface of the moldboard. For example, wax has long been used by snowplow operators on the moldboard. Moldboards have also been permanently coated with various substances. However, such coatings eventually fail when struck by rocks, stones and other debris from the roadway which impact the moldboard under significant forces.
A number of various materials having extremely low coefficients of friction exist in the art. In particular, ultra high molecular weight polyethylenes have been developed and applied in industrial application where sliding contact is encountered, such as, for example, in wear strips, slide plates, bearings and bushings. Until recently, considerations relating to the mechanical properties of such materials have ruled out the suitability of such materials for use as a moldboard in a snowplow application.
On the basis of weight and cost considerations alone, various types of plastics, other than ultra high molecular weight polyethylene, have been used as moldboards in snowplows. The plastic is preformed into the desired curvilinear shape and applied flush against the frame where it is drilled and fastened in place in the same manner that the steel moldboard is conventionally applied to the frame. Depending upon the properties of the plastic and its durability, plastic moldboards have met with limited success.
The snow plow art was significantly advanced when a high molecular weight, polyethylene material was used as a moldboard to produce a durable, lightweight and significantly improved snowplow as disclosed in U.S. Pat. No. 4,803,790 (and its parent U.S. Pat. No. 4,845,866) to Ciula incorporated herein by reference. The plow disclosed in the ""790 patent comprises a conventional frame which includes top and bottom longitudinally extending mounting members approximately equal to the length of the plow blade and a plurality of vertically extending, transversely spaced brace members. Each brace member is secured at one end to the top mounting member and at its opposite end to the bottom mounting member and has inwardly curved, forward edge surfaces extending between the top and bottom mounting members. A generally rectangular and inwardly curved polyethylene moldboard of high molecular weight is attached by threaded fasteners to the top and bottom mounting members in a somewhat flexed or prestressed manner. The rearward surface of the attached moldboard is spaced away from the forward edge surface of the brace members a fixed distance to define a gap therebetween. This gap distance is normally sufficient to prevent contact therebetween during operation of the plow while permitting brace contact during excessive debris impact. More particularly, the moldboard resiliently flexes into and out of the gap during heavy or wet snow removal and this flexing enhances the transverse and rolling movement of the snow over the face of the moldboard. Yet the frame/moldboard mounting arrangement provides brace support for the moldboard when the moldboard is impacted with heavy debris to prevent moldboard fracture. For these reasons, the ""807 patent is a significant advance in the art.
This arrangement was improved upon in U.S. Pat. No. 5,088,215 to Ciula, also incorporated herein by reference. In the ""215 patent, the high molecular weight, polyethylene moldboard was molded with a desired curvature and the top and bottom molding mounting members changed to allow the moldboard to be snapped into or onto the frame and secured by fasteners in a conventional manner. While the ""215 patent improved the frame mounting arrangement, the gap between the moldboard and the brace members is maintained so that the moldboard retains its enhanced snow removal characteristics.
In summary, both designs have achieved considerable success not only because of weight reduction and cost considerations, but also because of the enhanced operation of the moldboard attributed to the characteristics of the polyethylene material and the utilization of the material""s ability to spring or flex into the gap designed mounting arrangement.
Snow plows are typically used in hostile environments and are subjected to cold temperatures, moisture, freezing rain, ice, salt, and severe impacts against fixed protrusions such as curbs and from rocks and debris from the roadway. During continued or protracted operation of the plow, debris from the road can lodge itself into the gaps between the moldboard and brace members. If the operator does not take time to periodically clean the gaps, they can become eventually full with solid debris with the result that the resilient mounting of the moldboard onto the frame, provided by the gap, is lost or diminished. More significantly, plow operating temperatures encompass such a wide temperature range, that water collected in the gap can freeze into ice or create ice pockets in the gap. In such instances the gap designed into the moldboard/frame mounting arrangement is lost or drastically reduced. While the moldboard still has superior snow removal characteristics attributed to its low co-efficient of friction, the enhanced ability of the moldboard to transversely move and roll the snow across the face of the plow is diminished.
Accordingly, it is a principal object of the invention to provide a mounting arrangement for a plastic moldboard in a plow which allows the moldboard to achieve its designed resilient deflection no matter what operating conditions the plow is subjected to.
This object along with other features of the invention is achieved in a vehicular plow of the type used to clear snow and like debris from roadways and similar surfaces which includes a plastic moldboard and a rigid frame secured to the vehicle on one side thereof and to which the moldboard is assembled on the opposite side thereof. The frame has at least one vertically extending brace member spaced from the moldboard over a portion of its length to define a vertically extending gap therebetween and a resilient material at least partially fills at least a portion of the gap whereby the moldboard is able to resiliently flex even if foreign material or foreign matter, which includes formation of ice or ice pockets in the gap as well as solid debris from the road, accumulates in that portion of the gap not filled by the resilient material.
In accordance with another aspect of the invention, the frame includes top and bottom longitudinally extending mounting members vertically spaced from one another by a plurality of the brace members transversely spaced along the length of the mounting members with the moldboard connected to the mounting members when assembled into the frame. The moldboard and the confronting portion of each brace member are inwardly curved to define the gap as an arcuate gap which may or may not be designed uniform throughout its length. The resilient material substantially fills each gap thereby preventing foreign matter from accumulating and stopping the moldboard from resiliently deflecting into the gap.
In accordance with a specific aspect of the invention the brace members are structural angle members, each brace being orientated to have a V-shaped cross-sectional configuration with the edges of the legs forming the V-shape being inwardly curved so that the leg edges and the back of the moldboard define the arcuate gap. The resilient material, when the moldboard is assembled in the frame, is interposed between each of the leg edges of each brace and the back of the moldboard to substantially or partially fill the gap by any number of resilient mass configurations, including, but not limited to:
a) the resilient material comprising a block of material positioned within the V of each brace member and extending beyond the leg edges to substantially close the gap; or
b) the block in (a) with a longitudinally extending opening therein, the opening being distended when the block of resilient material is compressed; or
c) the block in (a) or (b) having a cross-sectional configuration substantially in the shape of a V so that the block of material nests within the V-shaped configuration of a brace member; or
d) the resilient material is a vertically extending strip of resilient material interposed between each leg edge and the moldboard; or
e) the strip of (d) having a thickness approximately equal to the gap and adhesively secured to the moldboard; or
f) the strip of (e) secured to the moldboard by means of a cushioned, double-faced adhesive tape; or
g) the strip of (d) having a groove formed in one of its side, the bottom of the groove adapted to contact a leg edge and the sides of the groove adapted to contact the sides of a leg of the brace member; or
h) the resilient material is in the form a retrofit insert strip having an especially configured groove permitting the insert to be snapped into groove seating with a leg of a brace member after the moldboard has been assembled into the frame; or
i) the insert of (h) wherein the strip is triangular in cross-section configuration with a groove formed on a first side of the strip adjacent a second side of the strip which is in contact with the moldboard so that the first and second sides form an apex of the triangle whereby the insert is wedged into a groove seating position between the moldboard and a leg of a brace member.
In accordance with another feature of the invention, the moldboard is mounted to the mounting members by fasteners and the resilient material extends a distance substantially equal to the gap (or even greater than the gap) so that the resilient material contacts the moldboard (or is even slightly compressed) as the fasteners are tightened to assure that no gap is present when the moldboard is assembled in the frame whereby any accumulation of foreign matter in the gap is prevented while maintaining a resilient mounting of the moldboard to the frame.
In accordance with another feature of the invention, the moldboard is mounted to the mounting members by fasteners and the resilient material extends a distance less than the gap when the moldboard is assembled in the frame whereby any accumulation of foreign matter in the open space of the partially filled gap does not prevent the moldboard from resiliently deflecting into the gap.
It is yet another feature of the invention to provide a method of assembling a plow comprising the steps of a) providing a polyethylene moldboard; b) forming a frame by securing on one side of top and bottom longitudinally extending mounting members a plurality of vertically extending brace members; c) securing the moldboard to the opposite side of the mounting members and in the process thereof forming a gap between confronting surfaces of the brace members and the moldboard; and d) affixing a resilient material to the moldboard and/or the brace members before or after assembly of the moldboard into the frame to at least fill a portion of the gap.
It is thus an object of the invention to provide a plow with a plastic moldboard assembled in a frame in a resilient manner which is able to resiliently deflect notwithstanding the accumulation of foreign material, including ice build up, between the moldboard and the frame.
It is another object of the invention to provide a plow with a plastic moldboard assembled in a frame in a resilient manner which prevents accumulation of foreign matter between the moldboard and the frame while allowing the moldboard to achieve designed resilient deflection.
An important object of the invention is to provide apparatus and method for retrofitting existing plows having plastic moldboards resiliently mounted in a frame with a mounting arrangement which positively assures that the moldboards resiliently deflect notwithstanding adverse conditions resulting from the harsh operating environment of a snow plow.
Yet another object of the invention to provide a plow with a plastic moldboard having any of the characteristics described above which can be easily assembled or repaired if necessary.
Still yet another object of the invention is to provide a plow with a plastic moldboard having any of the characteristics described above which is relatively inexpensive.
Yet another object of the invention is to provide a snowplow frame mounting arrangement for a high density, polyethylene moldboard which positively insures designed flexure of the moldboard notwithstanding any adverse effects attributed to the snowplow""s operating environment.
These and other objects and advantages of the present invention will become apparent from the following Detailed Description of the Invention taken in conjunction with the accompanying drawings which are described below.